There are currently between 1.2 and 1.5 million lower-limb amputees in the U.S., and the number of amputations associated with diabetes is expected to triple in the next 15 years. Most amputees are over 65 years old, and this population is not well-served by the "energy-storing" feet that are popular with younger, more-active amputees, because this stiff athletic technology is inherently suited to running and cannot be used by the majority of lower-activity amputees. Currently available "conventional" feet are based on decades-old designs that do not enable amputees to walk normally or efficiently. Tensegrity's innovative, patent-pending foot prosthesis being developed under this multi-phase SBIR project is designed to meet the needs of the majority of amputees who simply want to walk comfortably. Phase I results demonstrated the potential for Tensegrity's novel foot design to result in a competitive commercial prosthetic foot;one that allows for more-efficient and more-effective walking than any prosthesis sold today. Tensegrity's successful 2-year Phase I project leads into a larger Phase II demonstration and validation effort focused on three Aims: 1) complete the design for a commercially ready prosthetic foot, focusing upon durability and the ease of manufacturability to ensure a high-quality product that provides for an efficient stride and a decrease in the applied load on the residual limb;2) acquire ISO certification for the product;and 3) run a beta test with 50 amputees to verify that the new prosthetic foot will be maintenance-free and durable for at least 6 months after initial fitting. Phase II success will set the stage for Tensegrity's Phase III commercialization effort. This exciting new foot prosthesis will appeal to and will greatly benefit the nearly half-million amputees who have difficulty using current technology. Phase II R&D will involve 1) manufacturing "test feet" from a design proven in Phase I, and 2) completing a variety of bench, fatigue, and human subjects tests on the prosthetic feet. Human testing will include instrumented gait lab testing and metabolic efficiency/oxygen consumption testing. Phase I data indicates that this new foot can be produced at a lower manufacturing cost than current leaf-spring foot designs and will be able to be fitted to patients in 40% less time. This next-generation Tensegrity prosthetic foot design will provide a higher quality of care and quality of life for lower-limb amputees, who will be able to return to activities they once enjoyed because of the greatly improved biomechanics of the foot. We expect that Phase II research results will produce a biomechanically superior, more-comfortable prosthetic foot design ready for commercial production and widespread domestic and worldwide sales. PUBLIC HEALTH RELEVANCE. This SBIR Phase II project is designed to demonstrate that Tensegrity's next-generation prosthetic foot can improve the quality of life and health for a large percentage of current and future amputees who are severely underserved by the prosthetic foot designs available today. Successful prototyping, validation, and commercialization of this new prosthetic foot will benefit 1) lower-limb amputees, who will enjoy a more-normal life with fewer visits to the doctor for pain control because of more comfortable fit and stride;2) our health care industry's overburdened prosthetists, who will be able to profitably serve more patients in less time;and 3) our nation's financially overburdened health- care system, which will benefit from hundreds of thousands of amputees who are mentally and physically healthier because of this new prosthetic technology